Regular deep breathing exercises are commonly prescribed for patients following any significant chest or abdominal surgery, to minimize the incidence of pulmonary complications. Pain, analgesics, and the patients' fear of re-opening an incision produces a change in the patients' normal pattern of breathing, and as a result, deep inspiration often fails to occur postoperatively unless the patient is encouraged to participate in deep-inspiration exercises, or is forced to do so through mechanically-controlled inhalation therapy machines. Various self-use mechanical devices are also frequently used in deep-breathing exercises. Many of these devices additionally provide biofeedback and monitor the patient's progress. These devices are generally referred to as "incentive spirometers". However, these self-use devices monitor total volume of air in the lungs and do not encourage nor monitor the specific contraction and expansion of the lower lobes of the lung, which are most susceptible to infection. Specific exercising of the lower lobes of the lungs is critical for proper respiratory exercise, to minimize the onset of pulmonary disease, such as pneumonia or atelectasis. This is because fluids tend to accumulate in the lower lobes of the lungs, and exercise of only the upper lung areas encourages this migration of fluids. The prior art devices are not highly effective in achieving expansion and contraction of specific lower lung areas, as patients have a tendency to cheat to avoid the discomfort and pain associated with lower-lobe exercise.
For example, patients can defeat the purpose of many of the prior art devices by using their upper chest only, or by narrowing their lips to increase the measured air flow rate, or by not starting each exhalation with a fully-expanded chest, or each inhalation with a fully-contracted chest. To avoid this cheating, and to compensate for the deficiency of the prior art self-use devices, therapists sit in front of their patient, place their hands on and around the patient's lower chest, with thumbs touching after the patient has fully-exhaled. The therapist then requires the patient to cause the therapists' thumbs to move apart by requiring the patient to physically expand his lower chest cavity. This technique does achieve the desired result, but requires a therapist to administer the exercise, and does not lend itself to self exercise either in the hospital or at home.
To meet this need for an incentive spirometer which: (1) encourages the exercise of the lower portions of the lungs; (2) provides biofeedback to the patient to encourage a regular exercise activity, and, more importantly; (3) can be successfully and effectively used by the patient himself in an unsupervised environment, the inventors herein have succeeded in developing an incentive spirometer which includes a non-elastic belt of an adjustable length which can be secured firmly about the patient's lower chest, and which has a unique fastener joining the belt ends to provide a measured expansion of the belt as the lower chest only expands and to graphically indicate to the patient his progress in the exercise routine. To achieve this, one end of the belt is secured to a leaf spring inside the fastener, the leaf spring resisting withdrawal of that belt end from the fastener. Since a patient's ability to expand his lungs is greatest when his lungs are in their minimal expansion phase, the resistive mechanism within the fastener provides maximum resistance when the lungs are in their minimal expansion phase, with the resistive mechanism providing gradually decreasing resistance as the lungs expand, and gradually increasing resistance as the lungs contract.
A series of LEDs are progressively lighted to indicate the withdrawal of the belt, and a chime may also be preset to audibly sound after the belt has reached a designated position. The chime can be adjusted for different amounts of travel as the patient progresses with his exercise routine, and will always give a clear indication of the point at which the patient can relax. Additionally a numerical counter can be provided to count the total repetitions completed. Since the biofeedback mechanism provided by the LEDs and chime is adjustable, the incentive spirometer of the present invention can be used to provide a progressive developmental program of lower-lung exercise which can be visibly followed by the patient and/or therapist as either or both observe the LEDs being illuminated to indicate a greater expansion of the lower portion of his lungs. The progressive developmental program can be varied by increasing or decreasing both the required degree of expansion necessary to activate a pre-set LED and/or the number of required repetitions, as pre-established by the therapist.
The first LED is used to indicate the proper degree of belt tension; as the belt is fastened firmly around the user, the first LED is activated thus signalling to the user that the belt is fastened with a proper degree of tension. The first LED is a different color than the sequential LEDs which monitor lower lung expansion. This system provides the same degree of belt tension regardless of body size.
As these exercises can be uncomfortable, or even painful depending upon the surgery, it is important that the device create some interest for the patient, and possibly even capture his curiosity and fascinate him to encourage him to continue the exercise program. With the present invention, the successive flashing of the LEDs as the belt is withdrawn is visually attractive, and the chime which sounds at the end of the exercise is an audible reward for completing an exercise repetition to provide a sense of achievement and satisfaction. In some senses, the visual and audio feedback parallels that experienced through the playing of the various electronic games presently in vogue. If the optional counter is incorporated, even greater incentive is established.
Another important feature of the invention is the leaf spring which secures one end of the belt to the fastener. The leaf spring is of a negator type which provides a greater resistance upon initial deflection with a lessening resistance as the spring is further deflected. Thus, the greatest resistance is provided as the patient first starts to inhale, and a lesser resistance as the patient reaches the end of his inhalation motion. A most important feature of the invention is that the reverse is accordingly also achieved: as the patient exhales, belt resistance increases, helping to force as much air as possible out of the lower lobes of the lung, thereby assisting in the mobilization of accumulated fluids out of the lungs. These two resistive forces (decreasing resistance during inhalation; increasing resistance during exhalation) are currently produced with manual pressure by a therapist, in response to the anatomical strength of the muscles of the diaphragm, which becomes less effective as they reach the limits of their range of motion. The fastener may be constructed by plastic injection molding techniques, and easily assembled to minimize cost and make the incentive spirometer affordable to almost any patient for use at home. Adjustment of the belt is achieved through a swingable loop through which an end of the belt is inserted and then secured with suitable Velcro.TM. material.
These and other features and benefits of the incentive spirometer disclosed herein may be more fully appreciated by referring to the drawings and description of the preferred embodiment which follows.